HT740 Lockup Solenoid

[opus]

Anyone have one they are not using?  How about some description of installing one?  I found a link here but it was dead.

[luvrbus]

Simple if you use 1 solenoid tap the outer most test port at the governor and the test port for the converter,if you do it like Allison recommends it takes 2 solenoids one with a bypass in case the pressure reaches excess pressure. These guys here use 1 solenoid they don't like paying the 400 bucks for the bypass solenoid and buying or tapping the pan for the bypass to dump the oil back to the pan, I have a couple but don't know yet if I am going to sell or not

good luck   

[opus]

OK, maybe if you could, back up a few steps?  Solenoid?  What type of solenoid?  I have no clue how this works.

Again, this is for someone else.  Not sure how I get in the midst of all these.

I have a 643, I dont need one. 

[luvrbus]

Electric over hydraulic the solenoid (Skinner valve) opens sending transmission fluid to the converter from the governor port locking up the converter why does he even want one ? just for the Jakes in first gear 

[opus]

Yes, Jakes in first gear.  He runs the "grapevine" a bit and it gets gnarly.  Too fast for 2nd gear he says.

[opus]

Could you give me a part number or example, for the solenoid valve?  What is the required inlet/outlet diameter?

[Lin]

I did this project on my 647.  It keeps the transmission in lockup in 1st and 2nd when the Jakes are on.  I got the valve from Versa, and it cost somewhere in the are of $300.  I do not remember the part number, but if you call their tech support tell them what you want to do, and give them the specs, they can work out which part number it is.  You will then have to order it from one of their dealers.

It is a normally closed solenoid that goes in line from the high pressure port to the lockup port.  It must have an exhaust port that is plumbed back to the transmission pan.  Mine is just dumped back into the dipstick tube.  If you do not have an exhaust port, the pressure to the lockup port may not drop when you turn to Jakes off and will continue to keep the transmission in lockup.  There is also a waste port on the valve that spits a little oil each time the valve cycles.  I plumbed this one into the same line that goes to the dipstick tube.  It should be spec'd to, I think, 250 degrees F, so it needs Viton seals.   I do not remember the pressure spec right now, but it's pretty high.  Mine is wired through the buffer switch, which makes sure it only goes on when the Jake is on, cuts off when you accelerate, and cuts off at low rpm. 

I was sure I posted some stuff about the project on this board, but I could not find it when I searched.

[opus]

Thank you, I passed it on.